Automotive engine analyzer



April 2, 1957 E. A. sAMMls ETAL AUTOMOTIVE ENGINE ANALYZER 6 Sheets-Sheet l Filed Dec. 19, 1952 April 2, 1957 E. A. sAMMls ET AL 2,787,760

AUTOMOTIVE ENGINE ANALYZER Filed Dec. 19. 1952 6 Sheets-Sheet 2 April 2, 1957 E. A. SAMMIS ET AL AUTOMOTIVE ENGINE ANALYZER Filed Dec. 19, 1952.

5 Sheets-Sheet 3 /M WM ATTOR EY April 2, 1957 E. A. sAMMls ET AL 2,787,760

AUTOMOTIVE ENGINE ANALYZER Filed Dec. 19. 1952 6 Sheets-Sheet 4 ATTORNEY April 2, 1957 E. A. 'SAMMls ETAL 2,787,760

AUTOMOTIVE ENGINE ANALYZER Filed Dec. 19. 1952 Y 6 Sheets-Sheet 5 (foe ATTORNEY United States Patentl AUTOMOTIVE ENGINE ANALYZER Edward A. Sammis, Roslyn Heights, Harry D. Smith, New Hyde Park, and Eugene P. Vehslage, Great Neck, N. Y., assignors to Sperry Rand Corporation, a corporation of Delaware Application December 19, 1952, Serial No. 326,891

24 Claims. (Cl. 324-16) This invention relates to ignition testing means for internal combustion engines, and more particularly, to automotive engine analyzers.

The principal operating conditions for good automotive engine performance are:

(a) Proper air-fuel mixture.

(b) Good combustion chamber compression.

`(c) Properly timed ignition which adequately tires the mixture.

ignition troubles are not easily isolated, since they may -occur from many different mechanical and electrical pai'ts which are dynamically interrelated in a fairly complex manner. Therefore, the conventional cut-and-try method of removing, testing and replacing ignition parts one at a time is extremely wasteful of manpower. In conventional practice, many ignition parts, such as spark plugs, coils and distributors, are removed and bench tested. This removing of parts is very wasteful of manpower and does not provide the optimum dynamic testing with the part performing its normal function in an operative system. Furthermore, the conventional approach will not locate faults in parts not removed, intermittent faults, or yfaults occurring only under dynamic conditions. In conventional practice the separately removed parts are then :statically tested by a number of separate nonrelated instruments which must be separately connected, interpreted and evaluated, and then reconsidered and evaluated again in terms of complete system performance. This system correlation and evaluation requires a high level of skill :and experience by the mechanic. Quite often the cost of removing, testing and replacing ignition parts exceeds the lcost of the parts themselves. Quite often good parts are scrapped because reliable and econo-mic testing means are notravailable.

Therefore, there is a need for instrumentation which is integrated to provide complete andsystematic dynamic testing of automotive ignition systems. Such apparatus will eliminate the manpower and material waste in aimless hit-or-miss testing, removing and replacing of parts, in separately testing the parts with separate instruments and then trying to evaluate the separate static test data in terms of dynamic system performance.

The present invention provides an automotive engine analyzer which fulfills this need. The present invention provides integrated measuring apparatus, which is easily connected and which may be used to dynamically test ignition system performance in a scientic and systematic manner.

More specifically, by using a distributor adapter and clipping two leads across'the breaker points, it is possible with the present invention to fully check operation of the ignition system in the following respects:

A. (l) Determine if all the sparkplugs are ring properly. (2) Identify particular faults of a particular spark plug, i. e., shorted and open circuits, fouled and wide gapped plugs.

2,787,760 .iu-Patented Apr. 2, 19547 rice (3) Determine whether or not breaker-point operation is good. (Free of arcing or bouncing.)

(4) Check the breaker-point gap.

(5) Measure the basic spark timing.

(6) Determine whether respective spark advances are operating properly.

(7) Measure the cam angle.

(S) Determine relative performance rating factor of the ignition system.

B. Further information about calibration of the distributor and performance of the engine can be determined by making vacuum connections with rubber hoses from the invention to the distributor, carburetor, and manifold. By this means: g

(l) Vacuum advance may be separated from centrifugal advance. (Any desired vacuum may be applied to the distributor.)

(2) Pressure developed lat the carburetor may be verified over a range of engine speeds.

(3) Manifold vacuum may be read.

C. By shorting spark plug leads to make the engine run on two cylinders'.

(l) Relative power outputs of respective pairs of cylinders can be determined by noting the speed and manifold pressures for each pair at the Asame throttle setting.

(2) The engine may be power-timed at the approximate mid-range of the respective advances by rotating the distributor to obtain maximum speed at a given throttle setting. This is made possible by the unusual sensitivity of the tachometer of the present engine analyzer.

Accordingly, a principal object of the invention is to provide a new and improved automotive engine analyzer.

Another object of the invention is to provide an automotive engine analyzer for systematically and dynamically testing automotive ignition systems without affecting the operation thereof. f

Another object of the invention is to provide new and improved engine analyzing means for testing an automotive engine without removing any parts.

Another object of the invention is to provide integrated instrumentation for dynamically testing automotiveengines.

Another object of the invention is to provide new and improved means for dynamically checking spark plugs without removing them from the engine.

Another object of the invention is to provide new and improved means for checking an automotive ignition system under various speed and load conditions.

Another object of the invention is to provide new and improved means for checking automotive spark timing.

Another object of the invention is to provide means for checking the cam angle of the breaker points under .various conditions of speed and load.

Another object of the invention is to provide new and improved means for checking the spark advance under various conditions of speed and load. Y

Another object of the invention is to provide means for measuring the distributor centrifugal spark Vadvance under various conditions of speed and load. y

Another object of the invention is to provide means for measuring the distributor vacuum advance under various conditions of speed and load.

Another object of the invention is to provide an engine analyzer having means for producing patterns illustrative of specic malfunctions.

Another object of the invention is to provide an engine analyzer comprising a cathode ray indicator, a sweep generator for the cathode ray indicator which is ymechanically connected tothe engine, in combination with an electronic tachorneter, a timing light, and a timing pulse generator.

Another object of the invention is to provide an automotive lengine l'analyzer comprisinga cathode .rayindica tor wfor:providing patterns illustrative of various engine faults in combination with a tachometer, a timing light, and a timing pulse generator for coordinating the yaction of the timing light and acathode ray-indicator.

Another object of the invention'is to provide an automotive engine analyzer comprisinga cathode ray indicatorforprovidingpatterns illustrative of various engine faults in combination with a .tachometen a timing light, and Sa timing pulsesgeneratorfor coordinating the action ofthe timingl-lightvand -a cathode ray indicator, in Vcombination with means for measuring and `controlling the vacuum pressure 'derived from the engine.

Another object of the invention is to provide new and improved adapter -meanscfor rconnecting the cathode ray indicator Vtothe automotive engine distributor.

Another object of the .invention is to provide an automotive engine analyzer rcomprising a sweep Vvoltage generator and tachometermeans `connected 'to .measure the slope of said sweep `voltage to ztherebyindicate engine lspeed.

Another object of the invention is .to provide an :intefgrated-instrumentation'system for detecting ignition faults.

These and other objects of the invention will be ap- .'.parent from` the lfollowing specification and drawings, of

ltions;

n"Fi-g. 8Iis Eafgroup` of "cathode rray patterns Villustrative of various faults detected by the invention.

F.ig. f1 illustrates an vembodiment ofthe invention'which 'icom'prises gener-allya cathode `ray indicator 1, 'a sweep `circuit 2 connected to the engine under test to provide a sweep-'voltage of variable direct current (D. Cl) level to '.tl'ie cathode ray indicator toselect particular cylinders,

armulti range tachometerjcircuit 3 connected to the'swep generator-circuit to provide an accurate indication of tl'ie' engine ispeed, a timing pulse'generator 4 connected to the sweep circuit 2 and adapted to provide variable phase `synchronous pulses to the cathode rayY indicator 1 and the 'timing light 5. The timing light 5 may be a commercialy available timing light of the type as used lin Vservice stations for illuminating the indexed engine ily wheel in stroboscopic fashion. ln'conventional practice the vtiming light visconnected to the number one spark plug and tires in 'synchronisrn therewith.

The vertical detlection'plates 6 of the cathode .ray indicator are coupled tothe breaker points 7 of the auto- 'motive equipment under test. The performance rating means 8 comprises a variable resistance 8 connected acrossV the. points "77. The resistance S -maylbevdecreased thereby reducing the spark potential to Adetermine the value at which speed drops -oif orone or-:more spark plugs s top tiring, as will Abe more fully described hereafter. The potentiometer 8' is calibrated toprovidevan arbitrary figure of merit called the performance rating.

' Fig. 1 also shows several components of Athe .auto- `mcbi1e engine `ignition system vcomprising -thebreaker .points 7,.previonsly mentioned, which are Aopened by-the cam 10 of the distributor which is rotated in synchronism distributor shaft 12. The r"automobile battery 13 is connected to the primary 14 of the ignition coil, the secondary 15 of which is connected to the distributor rotor l1, and the condenser 16 isconnected across the distributor breaker points 7 in the conventional manner.

The automotive distributor '.-19`o`pera`tes in an entirely conventional manner. The distributor shaft 12 is me- 44clia'nically rconnected t'o'the engine (not shown) and rotates with the engine atlhal'f engine 4speed thereby causing the cam i0 to open the points 7 to provide a spark to thc distributor rotor 11. The distributor rotor 11 turns also, causing the `spark to re the respective spark plugs.

The sweep circuit2 comprises several components which will now be discussed. The rotating potentiometer 20 is mechanically connected to the distributor shaft 12 by means of a distributor adapter, as will be more fully discussed in connection with Fig. 6. The rotating potentiometer is energized by a direct current (D. C.) power supply 21. The horizontal position control 22 is provided to vary the direct current(D. C.) level of the sawtooth sweep voltage obtained from the rotating potentiometerfZl). .It comprises .a potentiometer 22' which is connected in parallel with the rotating potentiometer with its wiper arm 23 grounded through a resistor. The s awtooth sweep voltage-is taken between the arm 20 lofthe rotating potentiometer 20 and the grounded arm 23 of the-horizontal position control 22.

Therefore, as the position control Aarm 23 is moved, it will vary the direct current (D. C.) level of the sweep voltage which is applied tothe filter and shaping circuit 24. This varies the timing of the sawtooth wave relative to the engine cycle.

The filter and shaping circuit 24 operatesto smooth and `shape the waveform, as rwill be more fully explained .in connection with Fig. 2. The output -of the viilter and shaping 4circuit 24 is connected'to sweep length control circuit 2 5 which may comprise a switch 38 and voltage .divider 18. `The output-of the .sweep-length control 25 .is'applied to sweep amplifier 26. YThe amplifier 26 is ,preferably a'direct current (D. C.) amplier, the output voltage appearing across thedistributor breaker points.

'Ihehorizontal or ltirnecomponent of the pattern is provided by the sweep circuits which have been discussed.

lOne of `the primary problems inthe present invention is to provide an adequate stabilization of the length of the trace of the cathode ray tube, .-in view of the fact `that the enginehas a very large variation in speed of approximately 'a A10 to l ratio. The engine driven potentiometer 20 provides a trace having the same length regardless of engine speed. Conventional electronic cathode ray sweep circuits which are triggered-once per cycledo'not have automatic length stabilization 'and if employed would cause the length of the 'pattern to become larger or smaller as the engine speed varied. Ifproper stabilization of the sweep length wereV not provided, the pattern would become very small at high speeds so that the patterns would be dificult to read and the space of the cathode ray indicator face would not be fully utilized. It is `not believed feasible to use a triggered electronic sweep ,generator'for the speed range `of`asjgreat"as`tn tonne, whichV is the requirement in an automotive ng'ine analyzer, since it would be costly and diicult to achieve. 'T his isfa primary reason for using 'the rota'tingpotentioineter rather -th'ancn'entional trigger comprises a sensing circuit`30 which `measures the slope of the sawtooth wave derived from the potentiometer 20.

The slope of the sawtooth wave is a function ofthe engine Speed and the output of the sensing rcircuit 30 which is proportional thereto is connected to the vacuum tube voltmeter 31. The meter 32 is responsive to the vacuum .tube voltmeter input and is :calibrated to provide a direct reading of engine speed (R. P. M.) in revolutions per minute. The tachometer has a very sensitive scale for tuning the engine to optimum performance. 1t reads peak speed as engine variables are changed.

The timing pulse generator circuit 4 comprises a pulse shaping and amplier circuit 40 which differentiates and amplifies the sawtooth wave applied to it from the output of the filter circuit 24 to provide a timing pulse at the instant the sawtooth crosses zero voltage. The output of the pulse Shaper and amplifier cir-cuit 40 is connected to the vertical plates 6 of the cathode ray indicator 1. The same output is connected to the high voltage output stage 41, the output of which is connected to the timing light 5. The timing pulse generator operates to provide a timing pulse in the cathode ray indicator 1 in synchronism with the operation of the timing light 5. Therefore, as the timing light illuminates the y wheel in stroboscopic fashion, ythe time of the light flash is indicated on the cathode ray indicator where itm'ay be used to measure basic timing and spark advance in connection with the ignition patterns, as will be more fully described.

Fig. 2 illustrates a schematic diagram of the embodiment of Fig. 1. The sweep generator 2 comprises a rotating potentiometer 20, the movable arm'Ztl of which is driven by the engine distributor shaft 12. The potentiometer 22 is :connected toA 'a source of power 21 and also in parallel with the potentiometer 20; the potentiometers variable top 23 is grounded through a resistance. The variable tap 23 is adapted to be adjusted by the cylinder selector knob 27 which indicates Ia particular cylinder on the indicator card 27'. The sweep voltage 'at point A is the voltage developed across the rotating potentiometer 20, plus a variable part of the selector or direct current (D. C.) level potentiometer 22', since the movable arm '23 of the potentiometer 22' is at ground potential. When the selector potentiometer arm 23 is at the midpoint, the sawtooth voltage Will be centered about ground potential, and when it is shifted the sawtooth is shifted because of the change in direct current (D. C.) level. Therefore, when the knob 27 is moved, shifting the sawtooth voltage, the pattern from a particular cylinder may be centered on the cathode ray tube. A direct current (D. C.) source of voltage 21 is connected across the sweep generator potentiometer. The double pole, double throw reversing switch 28 is provided since some distributors rotate clockwise and some counterclockwise.

The sawtooth voltage developed by the sweep generator '2 appears at point A, as is shown in waveform A, Fig. 3. The waveform is rather rough due to the steps produced by the rotating ami 20 jumping from wire to wire of the potentiometer winding 20. The waveform at point A, Fig. 2, is smoothed out by the filter and shaping circuit 24. The lter comprises R. C. network resistor 33 and condenser 34 which have a time constant large enough to smooth the waveform. However, this large time constant would introduce an undesirabledistortion, as shown in the Waveform B, Fig. 3, which is especially objectionable because the retrace has a trailing edge which would interfere with the next sweep. In order to clip this retrace, 'theV condenser 34 is discharged during the retrace period by the thyratron tube 35 which is triggered by the triode 36. This clips the retrace, as shown in waveform C of Fig. 3, which represents the signal at point C. The plate of the triode 36 is also connected to provide a blanking pulse to the cathode ray indicator 1 during the retrace.

The output of the filter and shaping circuit 24 at point C is applied to a potentiometer 18 which is the sweep length adjustment. The switch 38 also connects to the .taps on a voltage divider39to provide predetermined sweep length control. The sweep length control circuits are adapted to change the sweep length from a relatively few crankshaft degrees to the full engine cycle so that either one selected cylinder pattern, or all the cylinder patterns, may be shown.

The output of the sweep length control circuits is connected to direct coupled amplifier 26 which contains two stages 52, 53 of conventional push-pull amplification. The output of the amplifier 26 is connected to the horl- Zontal deflection plates 9 of the cathode ray indicator 1.

The input fromthe primary ignition coil, which is the voltage occurring across the breaker points, is connected by means of leads 61 through switch 66 and coupled to the vertical deflection plates 6 of the cathode ray indicator. The performance factor means 8 comprising a resistance 3' may be connected across the breaker points by switch 62. This provides means for arbitrarily lowering the potential applied to the spark plugs. By gradually lowering the potential, the plugs in poorest condition will stop tiring and may be detected. Also the level at which engine speed drops otf is a measure of general .ignition condition. By using the performance rating means with a sensitive tachometer, we obtain a reference and thereby make readings reproducible.

The invention is not limited to showing merely the ignition patterns but any other indiciurn of performance such as vibrations may also be indicated by connecting the vibration pick-up 65 to the cathode ray indicator through amplifier 64% and switch 66. This will provide a pattern which may be used to identify various vibrations during the engine cycle, for instance detonation or knocking. The double pole, double throw switch 67 is provided to reverse the polarity of the various patterns, if desirable.

The cylinder selector knob 27 is indexed by short circuiting one spark plug, for instance, the number one spark plug, to obtain an easily identifiable pattern of that cylinder. The knob 2'7 is then turned relative to the card 27 so that the knob points to cylinder number one. The body of the rotating potentiometer 2t) is then turned to center the shorted pattern. (This is preferably done with the expanded or fast sweep selected.) The card 27 must be numbered properlyr corresponding to the tiring sequence of the particular engine and different cards are required for engines having a different number of cylinders or different firing sequences. For instance, one card Will be required for six-cylinder engines and another card for eight-cylinder engines, and diderent cards are required for in-line and V-type engines. A very few cards will cover practically all automobiles of popularmakes. The inner card 27 having the degree marks is not connected to any other part but is free to rotate. It is used to accurately measure the number of degrees between any events displayed on the cathode ray tube.

The tachometer circuit 3 comprises a sensing circuit 3ft which measures the slope of the sawtooth wave from the Wiper arm Ztl of the rotating potentiometer 20. The input sawtooth waves are connected to a differentiating circuit comprising resistors 43 or 43 and condenser 44. The time constant of the differentiating circuit may be changed by the switch 45a. The output of the differentiating circuit is the waveform D, Fig. 3, having sharp negative puises. The sharp negative pulses of the waveform D are clipped by the shunt connected diode 46 and the remaining positive voltage pulses are conducted by the series connected diode 47 and smoothed by shunt condenser da to provide a direct current (D. C.) Waveform E, Fig, 3, having a voltage level proportional to the engine speed. This direct voltage is fed to a vacuum tube voltrneter 31. The range selection switches 45a, 45h, 45e and 45d are ganged together and connected to a single knob 49. i

The Vacuum tube voltmeter comprises two triodes 54 and 55 having a direct current milliammeter 32 connected between their cathode circuits. The current through tri.

9 load increases the vacuum decreases and thespring pushes diaphragm 99 yout moving the linkage in the direction'of shaft rotation thereby retarding the spark. The vacuum pressure for actuating the diaphragm is normally derived from the hollow tube 109' which is connected to the carburetor side of the carburetor throttle valve.

The vacuum control unit 102 of the present invention comprises a conventional vacuum gage 103 which is connested to a three-way valve 104 having two other input connections. One of the other connections .05 is connected to the intake manifold '96. The other connection 106 is connected to atmospheric pressure through shut olf valve 107 and to the vcarburetor side 1of the throttle valve 103 through the tube 109.

Fig. 7A `shows the three valve positions of valve 104 and the function of each. When the valve is in position I, manifold vacuum is applied to the distributor and the gage 103 measures that vacuum. In position Ii the gage measures the manifold vacuum, and in position Ill the gage measures the distributor vacuum.

When connecting the vacuum control unit 102 to the engine, the original dot-ted line connection 109 from the carburetor throttle valve to the distributor is disconnected and -reconnected to the vacuum control unit as shown. Secondly, the hollow tube 105 is connected from the three-way v-alve 104 to the in-take manifold. This connection may be made to the conventional windshield wiper lconnection point, if the Windshield wiper is connected directly to the manifold.

The `operational use of `the vacuum control uni-t is as follows. When the valve 10d is in position I, the gage will measure the manifold vacuum applied :to the distributor. This can be used to indicate whether the vacuum advance unit Iof the distributor is functioning properly.

When the three-way valve 104 is in position II, it measures the manifold vacuum and can be utilized as a conventional vacuum gage, the use of which is well known in the art.

The shut-off valve 10d may be used to shut off `the vacuum input to the distributor when it is desired to isolate and test the centrifugal `spark advance. The shut-E valve 107 provides means for connectingatmospheric pressure to the distributor vacuum advance unit for test purposes. The Iamount of vacuum applied to the distributor may be varied by adjusting the openings of valves R07 and 104.

Fig. 8 illustrates various patterns illustrative of typical faults occurring in the ignition system. Pattern A shows a normal ring pattern. The breaker points open and the spark plug tires at the point a and the spark continues until the point b as shown by the high frequency oscillations occurring from points a to b. The low frequency waves starting at points b are due to the iniductance in the primary circuit. The breaker points close atthe points c as is clearly shown on the pattern and remain closed until the next cylinder is tired at the point d. The intewal from c to d is the cam angle.

'Pattern B shows a shorted secondary pattern in which the low frequency 'components are moved to the right .relative to their position -as shown in the normal pattern A.

Pattern C shows an Iopen secondary pattern. The plug does not tire.

lPattern D shows a partial fouling of a spark plug.

lPattern E shows a badly fouled spark plug when the tiring is sharply curtailed.

Pattern F is caused by the spark plug having too wide a sap.

Pattern `G shows arcing at the breaker points. The arcing occurs at the point g and delays the tiring of the spark plug. y

v Pattern H shows an open arcing.

condenser. Note the severe Pattern I shows burning of the breaker points at'. point Pattern J shows breaker peint bounce illustrated by the".2 voltage rise at point m caused as the points bounce apart after being closed the point n.

Pattern K shows very wide breaker point spacing which results in the very small cam angle as shown at k.

Pattern L shows a normal multi-cylinder pattern.

Patterns M and N show series gap patterns which might be caused, for instance, by a wire pulling away .from a terminal.

TYPICAL ENGINE ANALYZER OPERATION PROCEDURE A. H ook-up Install distributor adapter 90, as shown in Fig. 6.

. Clip signal leads 61, Fig. 2, to breaker points, terminal 200, Fig. 7, and ground;

. Connect vacuum lines to distributor, carburetor, and

manifold, as shown in Fig. 7.

B. Operation l. Run engine at any convenient speed (for instance 1200 R. P. M) Grient No. l engine cylinder with No. l position on dial 27 by using shorted secondary pattern, as follows:

a. Ground spark plug No. 1 with a clip lead.

b. Select expanded sweep (single cylinder pattern).

c. Set cylinder selector knob 27 on cylinder No. l

on card 27.

d. Rotate body of rotating' potentiometer 20 relative to adapter to center shorted pattern.

2. Run engine at i200 R. P. M. (or any convenient speed) and examine ignition patterns; compare with standard patterns, Fig. S, if not familiar with pattern. Select cylinders with selector knob 27. Check for:

a. Spark plug operation: shorts, fouls, opens, wide gaps, series gaps.

b. Breaker point operation: arcing, bouncing, burning, gap spacing.

3. Measure performance factor. (Reproducibility of reading with sensitive tachometer 3 is used for reliably indicating drop in speed.)

a. Zero center tachometer 3 on sensitive scale.

b. Connect performance factor circuit 8 with switch 62;.

c. Put full resistance in circuit (0 position) and vary potentiometer S' to decrease resistance across points, thereby lowering spark intensity. Worst plugs having wide gaps and fouled contacts will stop ring first. Performance rating gure where speed drops off sharply is an indication of general ignition performance, and may be compared with a standard figure. Average readings are from 60-80. Any reading below 60 (above 25 ohms) indicates trouble.

At a given speed between 1000 and 2000 R. P. M. the value of resistance at which the engine speed drops 50 R. P. M. is an indication of general ignition condition. The value of resistance at which an engine speed drops 50 R. P. M varies'with different engines, but if this value isv known for a given engine in perfect operating condition, then if a similar engine drops olrp .at any higher value of resistance, it is a sure indication of trouble in the ignition system. This method provides a good way of deter-mining plug condition in lieu of putting a load on the engine.

4. To measure engine timing:

l.y Set the timing light 5 so that it illuminates ignition timing marks, for instance on the fly wheel. 2. Turn the cylinder selector knob 27 until the light S stroboscopically illuminates the timing mark on the crankshaft in proper register with the reference mark provided by the manufacturer.

eps-'airco Thetimingpip on the indeatortsee pattern A), Ijig. 8. should now line up with the'V left edge of the voltage amplitude' tiring pattern of the cylinder which the manufacturer uses for timing. p If the timing pip is to the left of the voltage pattern, the firing is retarded with respect to` the designed timing point. The amount retarded in degrees may then be accurately measured as follows:

1. Accurately set the vernier card 27, Fig. 2, so

that is opposite the pointer of knob 27.

2. Turn knob 27' to line up the timing pip with the left edge of the voltage pattern.

3. Read the amount retarded in degrees on the vernier scale 27 opposite the knob pointer.

5. Calibrate distributor:

l. Check vacuum advance against automobile manfacturers specifications by changing diaphragm pressure at constant speed. Measure start of advance and maximum advance as a function of diaphragm pressure.

a. Shut olf valve 108,

Open valve 107,

Turn three-way valve to position I,

Vary valve 107' and three-Way v alve to vary vacuum pressure. A typical advance starts at a vacuum of -7 inches of mercury and is advanced 8 degrees at 15l7 inches. Measure vacuum on gage 103. Measure advance as previously described.

2. Check centrifugal advances. Apply atmospheric pressure to diaphragm to disable` vacuum advance, and measure spark advance as a function of engine speed.

rt. Turn valve 103 off,

b. Turn valve 107 on,

c. Turn three-way valve to positionIIl. Measure advance at several speeds and compare with manufacturing specifications. A tolerance of i2" is allowable.

6; Measurement of cam angle:

The cam angle or dwell is the number ofdegrees that the breaker points remain closed between any two cam lobes;

l. Turn knob 27 to select cylinderpattern.

2. Turn knob 27 to put `timing pip at breaker point closing (point c ofpattern Fig. 8).

3. Zero the degree card 27".

4. Move knob 2.7 to move the next pattern over to the timing pip. The number of dgreesof cam angle may be read from the degree card 27".

7. Power timing:

The sensitivity of the tachometer provides means for very accurately timing the engine under load conditions) To conclude, it is seen that the present irivention'provides integrated instrumentation which is adapted to be quickly and easily connected to'nn automotive'eng'ine. It provides means for completely and systematically'dynanil ically testing the ignition system for all usual malfunctions. The use of the present invention eliminates the manpower and-material waste in the aimless hit-or-miss testing, re-

moving and replacing of parts which are common in the conventional cut-andtryrnethod of servicing automobiles. By means of the present invention, theignitionsystem of nu automobile may be completely checked without re` moving any parts by makingfa fewv simple connections and fllowirgi'a, detailed cheek li's't. `The net result isthat the i'g'nition'systern is given a complete and systematic opera 'tional check ina `very short time. The invention may be operated by the average mechanic and will greatly increase his capabilities. The invention provides means foi' completely reorganizing and improving methods of testing automobile ignition systems and eliminates waste of manpower and parts which are necessary evils of the present un'systematic cut-and-try methods of testing.

The invention is not limited to use in detecting ignition malfunctions, but may be used with vibration or pressure pick-ups attached to the engine block to detect undesired knocking or detonation.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in thel above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

l. An analyzer for an automotive engine comprising aV lcathode ray tube having horizontal and vertical deecting means, said vertical deflecting means being connected to the ignition system of said engine, a sweep voltage generatorV connected to said horizontal dellecting means of lsaid cathode ray tube including a rotating potentiometer connected to said engine, a tachometer circuit connected to the output of said rotating potentiometer including means to measure the slope of said sweep generator output, n timing pulse generator connected to and adapted to be triggered from the output of said sweep generatorvmeans, one output of said pulse genera'tor'being connected to said vertical deduction means 'of said cathode ray tube, anda itning light connected tacliom'eter cir'ciiit connected to the output of said rotating potentiometer including means to measure the slpofsaid sweep generator output, a timing pulsegen- 4erator connected and adapted to triggered from the o'titput of said'swep generator means, one oiitpntof said pulse-'generator being connected to one of'said deflection mfeansfof said eatl1o`de"`1-aytttbc,and a timing light conrile'ctedto said timing ptilse generatorV whereby a timing marker pulse is providedon said cathode ray in coincidence with the flashing of* said timing light.

3? Ani analyzer for anl automotive engine comprising acathod-ray tube-'having horizontal and vertical detlectingrrneans;sadvertical'deecting meansV being connected to tlieiignitionlsysfemof said engine, sweep voltagcgene'A'ra-tor' meansihieans* to connect said sweep voltage generator tosaid engine comprising an adapter designed to t the distributor of said engine, a rotating potentiometer-connected tol said adapter, atachometer circuit connected to the output of said rotating potentiometer includin'g meansto measure theV slope of said sweep generator output, a timingpulse generator connected and adapted to be triggered fromfthe output of said sweep generator means, one output-,of said pulseA generator being connected to said vertical deflection means' of said cathode ray tube, and a timing light connected to said timingV pulse generator whereby a timing marker'plse is provided on saidl cathode r'ay in coincidence with the hashing of said timing light.

4. IonianF zinlyeru fowr'a'n internal combustionV engine,

having an ignition system and a distributor with a body and a removable cap, a cathode ray tube having horizontal and vertical deflectirjg means, said vertical deecting means being adapted for connection with the ignition system of said engine, sweep voltage generator means the output of which is connected with said horizontal deecting means, a potentiometer with a rotating tap connected to control said sweep voltage generator means, means for rotating said tap comprising an adapter arranged to removably tit between the body and cap of said distributor.

5. In an analyzer for an automotive engine comprising a cathode ray tube having horizontal and vertical deflecting means, said vertical deecting means being connected to the ignition system and said engine, variable phase sweep voltage generator means, means to connect said sweep voltage generator to said engine comprising an adapter designed to it the distributor of said engine, a rotating potentiometer connected to said adapter, and tachometer means connected to the output of said rotating potentiometer including means to measure the slope of saw tooth sweep voltage.

6. An analyzer for an automotive engine comprising a cathode ray tube having sweep generator means, said vertical deflecting means being connected to the ignition system of said engine, means to connect said sweep generator to said engine comprising an adapter connected to said engine distributor, said sweep generator means including a rotating potentiometer connected to said adapter, a timing pulse generator connected to the output of said sweep voltage means, one output of said timing pulse generator being connected to said vertical defiecting means of said cathode ray tube, and a timing light connected to said timing pulse generator.

7. An analyzer for an automotive engine comprising a cathode ray tube having variable phase sweep generator means, said Vertical deiiecting means being connected to the ignition system of said engine, means to connect said sweep generator to said engine comprising an adapter connected to said engine distributor, said sweep generator means including a rotating potentiometer `connected to said adapter, a timing pulse generator connected to the output of said sweep voltage means, one output of said timing pulse generator being connected to said vertical deecting means of said cathode ray tube, a timing light connected to another output of said timing pulse generator, vacuum pressure switching means connected to said engine and to said distributor to control the vacuum pressure applied to said distributor, and a vacuum gage connected to said vacuum switching means.

8. Means to check automobile spark plugs dynamically without removing them from the engine comprising a cathode, ray tube having horizontal and vertical deiiecting means, a sweep voltage generator connected to provide a sweep voltage v to said cathode ray tube, said generator means comprising a rotating potentiometer mechanically connected to said engine, and cylinder selector means connected to said rotating potentiometer. y

9. Means -tomeasure the timing error of an internal combustion engine comprising a cathode ray tube having horizontal and vertical deflecting means, a sweep voltage generator connected to the said horizontal deecting means comprising an adapter connected to said engine distributor and a rotating potentiometer connected to said adapter, a timing light pulse generator connected to the output of said sweep generator means, the output of said pulse generator being connected to said vertical deecting means, a timing light connected to said timing pulse generator, said timing light being used to illuminate said engine y wheel whereby the timing error may be read directly on said cathode ray indicator.

l0. In an analyzer for an automotive engine comprising a cathode ray tube having horizontal and vertical deecting means, said vertical detiecting means being connected to the ignition system of said engine; means to measure cam angle of automobile breaker points contb prising a variable phase sweep generator connectedV to said horizontal deiiecting means, a rotating potentiometer connected to'said engine and a timing pulse generator connected and adapted to put a timing pulse on said indicator, whereby the cam angle of the engine breaker points may be determined from said cathode ray tube pattern by moving the timing pulse a measurable amount from the beginning to the end of said cam angle portion of said pattern.

ll. in an analyzer for an automotive engine comprising a cathode ray tube having horizontal and vertical deiiecting means, said vertical deecting means being connected to the ignition breaker points of said engine; means to measure automobile spark advance comprising a sweep voltage generator connected to said cathode ray tube and including a rotating potentiometer connected to said engine distributor, means connected to said engine to measure vacuum pressure and means connected to control said vacuum pressure. v

l2. In an engine analyzer for aninternal combustio engine, a sweep voltage generator means comprising a rotating potentiometer, a low pass filter connected to the output of said rotating potentiometer including a shunt connected condenser, and a switch tube connected and adapted to discharge said condenser at the end of said sweep Voltage to clip the trailing edge of the sweep voltage caused by said lter.

13. In an engine analyzer for an internal combustion engine, a sweep voltage generator means comprising a rotating potentiometer connected to produce a sawtooth voltage, a low pass filter connected to the output of said rotating potentiometer including a shunt connected condenser, a switch tube connected and adapted to discharge said condenser at the end of said sawtooth voltage, and a second potentiometer connected in parallel with said rotating potentiometer, the arm of said second potentiometer being adjustable to thereby provide means for Vshifting said sawtooth voltage by moving said arm.

i4. An analyzer for an internal combustion engine comprising a cathode ray tube connected to the ignition system of said engine, a sweep voltage generator connected to said cathode ray tube including a rotating potentiometer connected to said engine, a tachometer circuit connected to the output of said rotating potentiometer including means to measure the slope of said sweep ,generator output, a timing pulse generator connected and adapted to be triggered from the output of said sweep generator means, one output of said pulse generator being connected to said vertical deflection means or" said cathode ray tube, and a timing light connected to said timing pulse geenrator whereby a timing marker pulse is provided on said cathode ray in coincidence with the flashing of said timing light.

l5. An analyzer for an internal combustion engine comprising a cathode ray indicator connected to the ignition system of said engine, a sweep voltage generator connected to said engine and to said cathode ray indicator for providing a sweep voltage thereto, and an electronic tachometer including a diierentiating circuit connected to the output of said sweep voltage generator to indicate the speed of said engine.

16. An analyzer for an internal combustion engine comprising a cathode ray indicator connected to the ignition system of said engine, a sweep voltage generator connected to said engine and to said cathode ray indicator for providing a sweep voltage thereto, an electronic tachometer connected to the output of said sweep voltage generator to indicate the speed of said engine, and a timing light with a timing pulse generator connected to the output of said sweep voltage generator and connected and adapted to energize said timing light and said cath ode ray indicator.

17. An analyzer for an internal combustion engine comprising a cathode ray indicator connected to the igniarem'eo tion system of said engine, a sweep voltage generator eonnec'ted to Asaid engine and' to said 4cathode-ray"indicator for providing' a' sweepvol'tage thereto, an electronic t'c'hoineter connected'to the outputy of said sweep'voltage generator to indicate the speed of-said engine, a timing light with a timing pulse generator connected to the'output of said sweep'voltage generator and connected,l and adapted to energize said timing light and'sa'id cathode ray indicator, and vacuum pressure means connected and adapted to measure and control ther vacuumVV toY the distributor of said engine. l

18. In an engine analyzer for' an internal combustion engine, a sweep voltage generator comprising a rotating potentiometer connected to produce' a sawtoothwave, a second potentiometer connected in parallelwith said first rotating potentiometer and having its wiper arm movable to vary the' direct currentV level of said sawtooth wave generated by` said rotating potentiometer, a filter circuit connected between the arm of said rotating potentiometer and ground to produce a modified version of said sawtooth wave, vand a restorer circuit connected to the output of said filter circuit and' adapted to clip the retrace of said modified version of said sawtooth wave.

19. In an engine analyzer for an internal combustion engine, a sweep voltage generator comprising a rotating potentiometer connected to produce a` sawtooth voltage, second potentiometer connectedrin parallel with said first rotating potentiometer and having its wiper arm movable to thereby vary the direct current level of' the saw'tooth voltage generated by said rotating potentiometer, a filter circuit connected between the arm of said rotating potentiometer and ground said filter circuit producing a modied version of said sawtooth voltage, a res-torer circuit connected to the output of said filter circuit and adapted to clip the retrace of said modified version of said sawtooth voltage, and means connected to the output of said restorer circuit for varying the amplitude of said modified Version of said sawtooth voltage.

20. ln an enginel analyzer, a cathode ray indicator, a sweep voltage generator connected to said engine to provide a sweep voltage to `said cathode ray indicator, a timing light for timing said engine by illuminating the fly wheel, and a timing pulse generator connected tothe output of said sweep voltage generator comprising means to differentiate said sweep voltage to provide a timing pulse, and means to apply said timing pulse to said cathode ray indicator and to said timing light in synchronism.

2l. An analyzer for an automotive engine having a distributor with a body and a removable cap, comprising a vibrationpickup attached to said engine, a cathode ray tube having horizontal and vertical detiecting means, said vertical detiecting means being connected to said vibration pickup, sweep voltage generator means the output of which is connected to Said horizontal deecting means, a potentiometer with arotating tap connected to control said sweep voltage generator means, means for rotating 'said tap comprising an adapter arranged to removably fit between the body and cap of said distributor.

22. An analyzer for an automotive engine comprising signal piel-:up means; a cathode ray tube having horizontal and vertical defiecting means, said vertical` deecting means being connected to said signal pickupmcans, sweep voltage generator means, means to connect said sweep voltage generator to said engine comprising an adapter designed to fit the distributor of said engine, a rotating potentiometer connected to said adapter, tachometer means connected to the output of said rotating potentiometer including means to differentiate the slope of saw tooth sweep voitage.

23. An analyzer' for an internal combustion engine'comprising a cathode ray tube having horizontal and vertical deflection means, saidl vertical defiection means being adapted to receive signals occurring during operation of said engine, a sweep waveform generator including a source of potential, a first potentiometer connected across said source and including means for mechanically connecting the tap thereof to be driven by said engine, a second potentiometer connected across said source and having an adjustable ground tap, and means connected to be controlled by the output of said sweep generator and by the potential at said adjustable ground tap and having its output connected to said horizontal deflection means, the response of said means being limited to a comparatively narrow range of Said sweep generator output embracing the potential of' said engine-driven tap, whereby a constant portion of said signals is visually displayed on said cathode ray tube for all engine speeds and desired signals occurring in an engine cycle are selected by adjustment of said. second potentiometer tap.

24. Means to check the operation of an automobile cngine comprising a cathode ray tube having horizontal and vertical deflection means, said vertical deflection means being adapted to receive signals occurring during operation o1 said engine, a sweep waveform generator connected to conti-ol the horizontal sweep of said cathode ray beam, said generator means comprising a potentiometer having a' tap' and means mechanically connecting said tap in driven relationv to said engine, and means for selecting a desired fractional portion of the signals occurring in an engine cycle for display on said cathode raytube.

References Cited in'the file of this patent UNi'ri-:D STATES' PATENTS 1,537,533 Lober May l2, 1925 1,537,670 Hammond May 12, 1925 2,190,713 Hintze el' al Feb. 20, 1940 2,256,601 West Sept. 23, 1941 2,282,340 Pieplow May 12, 1942 2,339,743 Norman Ian. 18, 1944 2,355,363 Christaldi Aug. 8, 1944 2,426,208 Hardy Aug. 26, 1947 2,518,427 `Lindberg et al. Aug. 8, 1950 2,575,494v Hornfeck Nov, 20, 1951 2,622,441 `Richardson et al. Dec. 23, 1952 FOREIGN PATENTS 156,352 Australia Dec. 11, 1952 

